Do you think you are ready for GMAT? One way to find out is to take the GMAT simulation test. Just like the real test you are going to sit, this computer-adaptive test will help you gauge your preparedness. If you do not "like" the score you got in this simulation test, then it is time to head back to your books and revise, or seek additional help.
Try the test now (test sets from GMAC, the official GMAT provider)
Or, Manhattan GMAT Prep's test.